How long do I have to submit my NCLEX- PN application post grad?

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How long do I have to submit my NCLEX- PN application after graduating? I graduated about 2 years ago and had a few hardships in my life which prevented me into going to take the test right away. I've never sent my application before and I just started attending refreshment courses and the DON at my school suggested I call the board to see if I qualify. Its almost impossible to get through so I was wondering if anyone knew?